Blast nozzle for forming silicate fibers



Nov. 14, 1967 s SPETH BLAST NOZZL'IE FOR FORMING SILICATE FIBERS Filed March 30. 1964 g INVEJZ'IOgLAT United States Patent 4 Claims. (in. 651) The present invention relates to blast nozzles of the type used for making silicate fibers from molten silicates such as glass fibers from glass, or mineral wool from silicate minerals.

More particularly, the present invention is concerned with an improvement of such blast nozzle arrangements which will reduce the risk of having the blast nozzle arrangement plugged up by silicate material passing therethrough and which will improve the quality of the produced mineral fibers.

Blast nozzle arrangements for the above mentioned purpose, namely for producing silicate fibers are well known and may be formed with an annular blast arrangement such as shown for instance in US. Patent 1,807,178, and German published application D.A.S. 1,067,572, or with nozzles defining an elongated gap through which the compressed blowing fluid and the silicate material pass, such as shown for instance in US. Patent 2,206,058, or German Patent D.B.P. 848,990.

All these blast nozzle arrangements comprise a channel open at both ends. Usually, the channel extends in a vertical direction and at one end thereof, usually the upper end, a stream of molten silicate material as well as one or more streams of blowing gas are introduced into the channel while at the other end, usually the lower end of the channel, a stream of blowing gas having fibers of silicate material distributed therethrough leaves the blast nozzle arrangement. The channel may be of circular cross section or may form a gap having an elongated rectangular slit-shape cross section.

Particularly blast nozzle arrangements forming an elongated gap-shaped channel make it possible to change the distance of the two halves of the blast nozzle arrangement forming the gap during operation of the same, as for instance described in German Patent D.B.P. 848,990. This makes it possible to reduce the width of the gap formed between the two nozzles of the blast nozzle arrangement to the smallest practical dimension. It is desirable to narrow the gap through which the molten silicate and the streams of blowing gas flow, however, if the gap becomes too narrow the danger will exist that molten silicate material, While passing through the gap and being sub-divided into fibers, might adhere to the walls of the gap and cause plugging up of the same which, of course, will lead to shut down of the nozzle arrangement and requires exchanging of the gap-forming nozzles for cleaning of the same.

Although blast nozzles of the type described generally are made of high grade steel and similar high grade and heat resistant materials in order to withstand the high temperature of the molten silicate and of the gaseous blowing agent, nevertheless, the useful life span of such nozzles was rather limited up to now. The gap-forming portions of the nozzles were found to be worn out after a few hundred operating hours and, particularly when it was desired to operate with a relatively narrow gap which is preferable from the point of view of producing fibers of the desired quality, erosions and corrosions of the gapforming wall portions were found after relatively short operating periods. Furthermore, in order to have the desired flow of the silicate material and the gaseous blowing agent, it is important that the gap-forming walls are smooth since upon erosion of the same eddy formation and turbulence formed in the blowing gas interferes with the formation of the fibers and might also be responsible for the early plugging up of the gap with molten silicate material.

It has been attempted to alleviate these difliculties by passing a cold air stream parallel and close to the walls of the gaps, for cooling the walls and for protecting the walls of the gap from attack by the molten silicate and the hot blowing agent. However, this does not appear to be a practical solution, not only because of the additional cost involved but also because it requires widening of the gap and withdraws energy from the hot blowing gas.

It is therefore an object of the present invention to overcome the above discussed disadvantages.

It is another object of the present invention to provide a blast nozzle arrangement for the effective fiber formation from silicate material which will permit prolonged operation with very narrow gaps.

It is a further object of the present invention to provide a blast nozzle arrangement which will be more resistant against attack by the molten silicate and the hot blowing gas, such as steam, than the blast nozzle arrangements of the prior art.

Other objects and advantages of the present invention will become apparent from the further reading of the de-. scription and of the appended claims.

With the above and other objects in view, the present invention contemplates in an apparatus for making silicate fibers such as glass fibers and mineral wool from molten silicates such as glass and silicate minerals, in combination, a pair of elongated substantially coextensive nozzle means located beside each other at approximately the same elevation and defining between themselves an elongated gap, the nozzle means both directing curtains of hot fluid downwardly through the gap, and elongated trough means located over the gap and having bottom outlet means extending along and aligned with the gap so that moiten silicate in the trough means will flow through the outlet means thereof to drop through the gap into the downwardly moving curtains of hot fluid to be converted into silicate fibers, the pair of nozzle means having wall portions which are respectively directed toward each other and define at least part of the gap and which at least directly adjacent the gap are made of a metal selected from the group consisting of nickel and of nickel alloys containing a'predominant amount of nickel.

Surprisingly it has been found that the disadvantages of the prior art blast nozzle arrangements can be elimi nated in an extremely simple manner by forming, in accordance with the present invention, at least the major part of the wall portions of the nozzle arrangement which wall portions define the gap through which the silicate melt and the hot blast gas flow and in which the silicate is subdivided into fibers, of nickel or of an alloy which predominantly consists of nickel.

It suffices for this purpose to form only the outermost layer of the walls of the gap of nickel in a thickness of about 1 mm. or slightly more than that. Alloys which consist predominantly of nickel, such as alloys which contain about nickel, for instance Nichrome alloys containing about 80% nickel and 20% chromium or Eleomet alloys, i.e., nickel-chromium steel alloys with relatively high silicon content, are harder and more resistant to wear than pure nickel, however, they are more easily wetted by the molten silicate than pure nickel.

Particularly when operating in a corrosive atmosphere, it is not only possible but frequently desirable to produce not only the gap-forming walls but the major portion of the blast nozzles of nickel or nickel alloys, for instance, of the type described above.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of a blast nozzle arrangement; and

FIG. 2 is a cross sectional view of the blast nozzle arrangement of FIG. 1 taken along lines IIII and also includes a cross sectional view of the feeding means for the molten silicate material.

Referring now to the drawing, it will be seen that two nozzles are arranged adjacent each other, each nozzle comprising an upper nozzle portion 1 and a lower nozzle portion 2. The distance of the two nozzle portions from each other and thus the width of the nozzle 3 is controlled by screws 4. Hot compressed fluid, such assteam, is introduced into the nozzles through conduit 5 and the steam will pass through nozzles 3 downwardly through gap 6 formed by wall portions 7 of the lower nozzle portion 2. At least wall portions 7 are formed of nickel. Molten silicate material 8 flows through the bottom outlet 9 of trough 10 into gap 6 and fibers will be formed thereof while the molten silicate flows downwardly through gap 6 in contact with the steam or the like emanating from the nozzles 3.

Surprisingly, it has been found, according to the present invention, that by forming at least wall portions 7 of nickel, plugging up and corrosion of the gap-forming Wall portions 7 is greatly retarded or eliminated and it will thus be possible to operate with a lesser width of gap 6 which in turn is advantageous for forming fibers of the desired quality.

The temperature of adherence, i.e. the minimum temperature at which the heated silicate will adhere to a metal wall is higher in the case of nickel as compared, for instance, with steel. Since only above this temperature of adherence the heated silicate will firmly adhere to the metal and on the other hand it will be possible to remove the silicate again below this temperature of ad herence, this quality of nickel is desirable for the purpose of the present invention.

However, the improvement which is found in forming gap-forming walls of the blast nozzle arrangement of nickel far exceeds any improvement which could be expected based solely on the higher temperature of adherence. Thus, for instance, the width of the gap of nickel plated nozzles could be reduced by and more below the minimum width under similar operating conditions which was required in the case of nozzles formed of steel and, nevertheless, the gap did not clog up. Furthermore, the blast nozzles according to the present invention withstand wear and tear to a much higher degree than a blast nozzle arrangement in which the gap-forming walls are formed of high grade steel. In fact, under otherwise equal conditions, the useful operating life span of blast nozzle arrangements according to the present invention is at least three times that of similar blast nozzles formed of high grade steel.

Comparison experiments which were carried out with other metals, namely metals having an even higher temperature of adherence than nickel, for instance, tungsten,

but which otherwise are somewhat similar to nickel, have shown negative results. In fact, blast nozzle arrange ments with gap-forming tungsten walls have a shorter life span than the conventional high grade steel nozzle arrangements. Thus, it is an entirely surprising result that the blast nozzle arrangements according to the present invention, i.e. blast nozzle arrangements in which at least the gap-forming wall portions consist of nickel permit narrowing of the gap and prolong the useful life span of the arrangement as compared not only with high grade steel, but also with blast nozzle arrangements in which the gap-forming walls are formed of metals having an even higher minimum temperature of adherence than nickel.

Without limiting the invention to any specific theoretical explanation, it might be that the fact that, for instance, tungsten is more easily wetted by the molten silicate than nickel, as well as the undesirable forming of oxide layers on the surface of the metal may be the reasons why nozzle arrangments of the type described, in which the gap-forming walls, or at least the major portions thereof consist of nickel give such surprisingly superior results.

Referring again to the drawing, which illustrates a.

nozzle arrangement in substantially its actual dimensions, it was not possible up to now to operate such nozzle arrangement with a gap having a width of less than about 6 mm. when the gap-forming walls consisted of high grade steel.

When reducing the width of the gap 6 to less than 6 -mm., in the case of high grade steel, the nozzle had to be replaced after a short period of time due to clogging up, orin any event, after about two hundred operating hours because of excessive wear.

However, by forming at least wall 7 of nickel, the distance between the opposite walls 7, i.e. the width of the gap 6 could be reduced to 3 mm. and it is thereby achieved that finer and longer fibers are produced with a lesser percentageof shot and, furthermore, that the useful life span or operating life span of the nickel equipped blast nozzle arrangement was increased to more than one hundred operating hours.

It will be understod that each of the elements described above, or two or more together, may also find a useful application in other types of blast nozzle differing from the types described above.

While the invention has been illustrated and described as embodied in a blast nozzle for producing. silicate fibers from silicate material, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an apparatus for making silicate fibers such as glass fibers and mineral wool from molten silicates such as glass and silicate minerals, in combination, a pair of elongated substantially coextensive nozzle means located beside each other at approximately the same elevation and defining between themselves an elongated gap, said nozzle means both directing curtains of hot fluid downwardly through said gap; and elongated trough means located over said gap and having bottom outlet means extending along and aligned with said gap so that molten silicate in said trough means will. flow through said outlet means thereof to drop through said gap into the downwardly moving curtains of hot fluid to be converted into silicate fibers, said pair of nozzle means having wall portions which are respectively directed toward each other and define at least part of said gap and which at least directly adjacent said gap consist essentially of nickel.

2. In an apparatus for making silicate fibers such as glass fibers and mineral wool from molten silicates such as glass and silicate minerals, in combination, a pair of elongated substantially coextensive nozzle means located beside each other at approximately the same elevation and defining between themselves an elongated gap, said nozzle means both directing curtains of steam downwardly through said gap; and elongated trough means located over said gap and having bottom outlet means extending along and aligned with said gap so that molten silicate in said trough means will flow through said outlet means thereof to drop through said gap into the downwardly moving curtains of steam to be converted into silicate fibers, said pair of nozzle means having wall portions which are respectively directed toward each other and define at least part of said gap, said wall portions consisting essentially of nickel and having a thickness, respectively, of the magnitude of one millimeter.

3. In an apparatus for making silicate fibers such as glass fibers and mineral wool from molten silicates such as glass and silicate minerals, in combination, a pair of elongated substantially coextensive nozzle means located beside each other at approximately the same elevation and defining between themselves an elongated gap, said nozzle means both directing curtains of hot fluid downwardly through said gap; and elongated trough means located over said gap and having bottom outlet means extending along and aligned with said gap so that molten silicate in said trough means will flow through said outlet means thereof to drop through said gap into the downwardly moving curtains of hot fluid to be converted into silicate fibers, said pair of nozzle means being formed of metal consisting predominantly of nickel and having wall portions which are respectively directed toward each other and define at least part of said gap.

4. In an apparatus for making silicate fibers such as glass fibers and mineral wool from molten silicates such as glass and silicate minerals, in combination, a pair of elongated substantially coextensive nozzle means located beside each other at approximately the same elevation and defining between themselves an elongated gap, said nozzle means both directing curtains of hot fluid downwardly through said gap; and means for introducing molten silicate located over said gap for dropping molten silicate into the downwardly moving curtains of hot fluid to be converted into silicate fibers, said pair of nozzle means having wall portions which are respectively directed toward each other and define at least part of said gap and which at least directly adjacent said gap consist essentially of nickel.

References Cited UNITED STATES PATENTS 2,190,840 2/1940 Kay 75-171 2,774,630 12/1956 Henry et al 1 X FOREIGN PATENTS 588,233 12/ 1959 Canada. 1,311,256 10/1962 France.

S. LEON BASHORE, Acting Primary Examiner. DONALL H. SYLVESTER, Examiner.

R. L. LINDSAY, Assistant Examiner. 

1. IN AN APPARATUS FOR MAKING SILICATE FIBERS SUCH AS GLASS FIBERS AND MINERAL WOOL FROM MOLTEN SILICATES SUCH AS GLASS AND SILICATE MINERALS, IN COMBINATION, A PAIR OF ELONGATED SUBSTANTIALLY COEXTENSIVE NOZZLE MEANS LOCATED BESIDE EACH OTHER AT APPROXIMATELY THE SAME ELEVATION AND DEFINING BETWEEN THEMSELVES AN ELONGATED GAP, SAID NOZZLE MEANS BOTH DIRECTING CURTAINS OF HOT FLUID DOWNWARDLY THROUGH SAID GAP; AND ELONGATED TROUGH MEANS LOCATED OVER SAID GAP AND HAVING BOTTOM OUTLET MEANS EXTENDING ALONG AND ALIGNED WITH SAID GAP SO THAT MOLTEN SILICATE IN SAID TROUGH MEANS WILL FLOW THROUGH SAID OUTLET MEANS THEREOF TO DROP THROUGH SAID GAP INTO THE DOWNWARDLY MOVING CURTAINS OF HOT FLUID TO BE CONVERTED INTO SILICATE FIBERS, SAID PAIR OF NOZZLE MEANS HAVING WALL PORTIONS WHICH ARE RESPECTIVELY DIRECTED TOWARD EACH OTHER AND DEFINE AT LEAST PART OF SAID GAP AND WHICH AT LEAST DIRECTLY ADJACENT SAID GAP CONSIST ESSENTIALLY OF NICKEL. 